Sack of Aquincum

The Sack of Aquincum occurred in 271 AD when the Germanic Quadi tribe, led by their king Helmut, conquered the Roman city of Aquincum in the province of Pannonia. The battle was the first of several Roman reverses along the Danube border.

Background
In 270 AD, the Roman Empire was thrown into an empire-wide civil war following the death of Claudius Gothicus, as his brother Quintillus was nominated by the Roman Senate to serve as emperor, while the Roman general Lucius Aurelianus was nominated as the new emperor by his Pannonian legions. Aurelian, who was in command of Rome's frontier legions, led his Legio I Dacica out of Sarmizegetusa and towards Italy to claim the throne for himself. This left the frontier undefended at a perilous time, as the Germanic barbarians were spilling across Rome's borders in search of new homes.

Among these tribes was the Quadi of Hercynia. The Quadi, along with the Marcomanni, had previously been fought off by Marcus Aurelius during the Marcomannic Wars of the mid-2nd century AD, but now capitalized on the chaos in Rome to invade Rome's frontier provinces. Their king Helmut assembled a large army of 3,040 warriors, and, unlike the Marcomanni and the Goths, he refused a peace offer from the Romans, as he was intent on avenging his people's defeat a century earlier.

Siege
In January of 271 AD, Helmut's massive army marched south to attack the unprotected Roman frontier settlement of Aquincum. The city was defended by just 440 troops under Gnaeus Verecundius Salinator, a tribune who had never held command of an entire army. His small force took up a protective stance, and they were overwhelmed by the surge of Germanic warriors and were annihilated; every Roman soldier was killed or captured. The Quadi showed no regard for civilian life, sacking much of the city and turning it into their regional base.